This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A197156 #24 Jun 02 2025 12:19:35 %S A197156 1,3,5,20,56,225,819,3333,13336,55231,229146,963284,4068503,17301000, %T A197156 73893082,317013121,1364917667,5896350458,25545737979,110968732581 %N A197156 Number of free poly-[3^3.4^2]-tiles (polyhouses) (holes allowed) with n cells. %D A197156 Branko Grünbaum and G. C. Shephard, Tilings and Patterns. W. H. Freeman, New York, 1987, Sections 2.7, 6.2 and 9.4. %H A197156 Peter Kagey, <a href="/A197156/a197156.pdf">Example illustrating that a(3) = 5</a>. %H A197156 Brendan Owen, <a href="http://web.archive.org/web/20061229103147/http://members.optusnet.com.au/polyforms/2dforms/polyhouses/index.htm">Polyhouses</a> (gives a(1)-a(10)). %H A197156 Wikipedia, <a href="https://en.wikipedia.org/wiki/Elongated_triangular_tiling#Prismatic_pentagonal_tiling">Prismatic pentagonal tiling</a> %Y A197156 Cf. A197157, A197158. %Y A197156 Analogous for other tilings: A000105 (square), A000228 (hexagonal), A000577 (triangular), A197159 (floret pentagonal), A197459 (rhombille), A197462 (kisrhombille), A197465 (tetrakis square), A309159 (snub square), A343398 (trihexagonal), A343406 (truncated hexagonal), A343577 (truncated square). %K A197156 hard,more,nonn %O A197156 1,2 %A A197156 _Joseph Myers_, Oct 10 2011 %E A197156 a(16)-a(20) from _Bert Dobbelaere_, Jun 02 2025